CID Model
year
Main Cap
Bolt
Bore Stroke Cylinder
Volume
Rod length
Rod ratio

Additional comments

366T 66-91 4 3.935 3.76 45.726 6.135 / 1.63 Cast iron tall deck truck block
366T 91-95 4 3.935 3.76 45.726 6.135 / 1.63 Gen. V, tall deck truck block, one piece rear main seal
366T 96- 4 3.935 3.76 45.726 6.135 / 1.63 Gen. VI, tall deck truck block, one piece rear main seal
396 65-69 2 & 4 4.094 3.76 49.496 6.135 / 1.63 --
402 69-72 2 & 4 4.125 3.76 50.248 6.135 / 1.63 --
427 66-69 2 & 4 4.250 3.76 53.340 6.135 / 1.63 Cast iron block, short deck
427 69 4 4.250 3.76 53.340 6.135 / 1.63 Aluminum block with cast iron liners, ZL-1, Very rare
427T 66-90 4 4.250 3.76 53.340 6.135 / 1.63 Cast iron Mark IV tall deck truck block
427T 91-95 4 4.250 3.76 53.340 6.135 / 1.63 Gen. V tall deck truck block, one piece rear main seal
427T 96- 4 4.250 3.76 53.340 6.135 / 1.63 Gen. VI tall deck truck block, one piece rear main seal
430 69 4 4.440 3.47 53.726 6.135 / 1.76 Aluminum race block with cast iron liners, extremely rare
454 70-90 2 & 4 4.250 4.0 56.745 6.135 / 1.53 Mark IV, short deck
454 91-95 4 4.250 4.0 56.745 6.135 / 1.53 Gen. V, one piece rear main seal
454 96- 4 4.250 4.0 56.745 6.135 / 1.53 Gen. VI, one piece rear main seal
465 70-71 4 4.440 3.76 58.216 6.135 / 1.63 Aluminum race block with cast iron liners, extremely rare
495 70-71 4 4.440 4.0 61.932 6.135 / 1.53 Aluminum race block with cast iron liners, extremely rare
495 72 4 4.440 4.0 61.932 6.135 / 1.53 Aluminum race block without iron liners, extremely rare
502 92-95 4 4.466 4.0 62.659 6.135 / 1.53 Gen. V HO. one piece rear main seal
502 96- 4 4.466 4.0 62.659 6.135 / 1.53 Gen. VI HO. one piece rear main seal, short deck
510 72 4 4.500 4.0 63.617 6.135 / 1.53 Aluminum race block without iron liners, extremely rare
510* 97- 4 4.500 4.0 63.617 6.135 / 1.53 Mark IV Bowtie, two-piece seal, short deck, cast iron
510* 97- 4 4.500 4.0 63.617 6.135 / 1.53 Mark IV Bowtie, two-piece seal, long deck, cast iron
* Actual CID of these blocks are 509 but Chevrolet has designated them as 510 so we do the same.
MARK IV / GEN V/VI Differences
Mark IV GEN. V GEN. VI CNC Bowtie
Rear Oil Seal Two-piece One-piece One-piece Two-piece
Main Oil Feed Left side oil pan rail Camshaft tunnel Camshaft tunnel Camshaft tunnel
Mec. fuel pump boss Yes No Yes No
Clutch Z-Bar pivot stud buss Yes No No Yes
Adjustable valve train Yes No No Yes
Rocker Covers Stanped steel Cast aluminum cast aluminum  
Oil Pans Use pan for two-piece main seal Use pan for one-piece main seal Use pan for one-piece main seal Must use pan for two-piece main seal
There are some more differences than the above.

Tommy Ledberg